The present invention relates to a contact element and to a SIM card contacting apparatus using such a contact element. More generally, the invention also relates to a contact element for a chip or smart card reader as well as to a chip or smart card reader using such a contact element.
As is well-known, chip or smart cards are used for various purposes, for instance as prepaid telephone cards. Such a telephone card allow the purchase to insert the card into a public telephone ant then make telephone calls equivalent to the amount of money paid for said telephone card. Chip cards are also used to identify members of, for instance, a health organization and so on. SIM cards derive their name form the words "subscriber identity module". SIM cards are frequently used in so-called cell phones, for instance to identify a subscriber of the respective telephone company. SIM cards are much smaller than smart cards, Thus, certain SIM card specific problems can occurs when they need to be "read" or contacted. Accordingly, the present invention relates in particular and preferably to contact elements and contacting apparatus for SIM cards and, more generally, to contacts and contacting apparatus for chip or smart cards.
In particular, the need to miniaturize cell phone to an extent as large as possible, sets high demands for the contact elements and the SIM card contacting apparatus using said contact elements to contact the contact areas or pads on the SIM card.
Due to the continuing strive for miniaturization, problems need to be addressed which can occur when contacting SIM cards. To provide for a reliable contact engagement with the contact pads or contact areas of a SIM card, a certain minimum pressure or a certain minimum force is required by means of which contact elements of a smart card contacting apparatus presses against the contact pads of the SIM card. So as to reach said minimum pressure when using contact springs, a certain spring path or spring deflection is required. With the presently used materials for the contact elements, the contact elements need to have a certain free length so as to provide for the necessary spring or deflection path without leaving the elastic range of the contact element. If the elastic range of the contact element is exceeded, then the contact element will remain deformed so that a reliable contact engagement is no longer warranted.
For better tolerance and for a safe and secure contact pressure, a relatively long spring or contact deflection path is desirable.
So far, contact elements were in substance linear leaf springs extending in one direction only. Thus, the required length of the contact elements determines for a certain spring or contact deflection path also the size of a contact block within which the contact elements are supported.
When designing reading and switching contact elements a beam element was used as a contact element. Said beam element was fixedly mounted at its; one end and was deflected by means of the chip or SIM card, thus creating the required contact element force applied to the contact area of a SIM card. Reading contact elements are contact elements which are typically used to "read" out information stored in the SIM card. Switching contact elements are used for instance to provide information whether a chip card, in particular a SIM card, is inserted into a respective contacting apparatus. Continuing with the description of the prior art, it should be noted that the contact element just described is subject to bending during its use. Frequently, the support of the contact element acts said a spring and is designed in trapezoidal form.
So as to reduce even more the requirement for space for a chip card or smart card in particular a SIM contacting apparatus, for instance to make a smaller cell phone possible, or to provide for the use of more components for the same size cell phone, the invention intends to optimize a SIM or chip card contacting apparatus with respect to the required space such that a reliable contacting engagement of the contacting areas of a SIM or chip card is not jeopardized.
It is, in particular, an object of the invention to maintain a small height or thickness of a contact block carrying the contact elements of, for instance, 1.2 mm and to reduce the distance of terminal portions, e.g. soldering terminal portions of the contact elements down to a small value. For instance, it is desired to reduce the distance between the terminal portions on opposite sides of the contact block from about 26 mm down to about 15 mm, due to the curvilinear structure of the contact element as opposed to linear or straight contact elements.